The Bacillus methanolicus strain C1, which is a methanol assimilating bacterium belonging to the genus Bacillus, has been known to have methanol dehydrogenase (also referred to with an abbreviation "MDH" hereinafter), which oxidizes methanol used as a carbon source into formaldehyde (Arch. Microbiol., 152, 280-288, 1989). MDH may be used for measurement of methanol content in a sample. In such a purpose, it is important to increase the specific activity of the enzyme, and means for achieving it have long been desired.
Arfman et al. has recently reported that a factor promoting this enzyme activity of MDH is contained in the Bacillus methanolicus C1. They purified a protein constituting the factor, and determined a partial amino acid sequence of the N-terminus of this protein (The Journal of Biological Chemistry, 266, 3955-3960, 1991). However, neither the whole structure of this factor and nor the genetic structure therefor has not been known at all.
By the way, Bacillus subtilis could not grow by utilizing methanol as an only carbon source, and therefore it has not been thought at all that this microorganism has methanol dehydrogenase, which is used for the first reaction of the methanol assimilation. In fact, when the present inventors searched known chromosome DNA sequences of Bacillus subtilis for a gene product or gene which has significant homology with the amino acid sequence and the nucleotide sequence of MDH of the Bacillus methanolicus C1, such a gene product or gene has not been found. Therefore, in microorganism not assimilating methanol like Bacillus subtilis, any activator of MDH has not been known, and its existence has not been expected.